The Arsenal striker Eduardo has been banned for two Champions League matches by Uefa having been found guilty of diving during the second leg of their play-off against Celtic.

Uefa's disciplinary panel made the ruling after a teleconference. The panel said the Brazil-born Croatia forward deceived the referee when he was awarded a penalty after a challenge by Artur Boruc, the Celtic goalkeeper, last Wednesday.

Eduardo converted the spot-kick to put his team 1-0 up on the night, after they had won the first leg 2-0. Arsenal won the match 3-1, progressing to the group stage 5-1 on aggregate.

Eduardo will miss Arsenal's Group H matches at Standard Liège on 16 September and at home to Olympiakos on 29 September.

Arsenal this evening condemned the "arbitrary" nature of Uefa's decision, but have not yet revealed whether they will contest the ban. A statement on their website read: "The club is disappointed with Uefa's decision to suspend Eduardo. We have been informed that we will receive a "reasoned decision" from Uefa by Thursday of this week. Once we receive Uefa's rationale, we will make a decision on the next steps.

"We have been deeply frustrated by the perfunctory and apparently arbitrary process that Uefa has followed in this instance. We believe it is imperative that Uefa's explanation for its decision provides clear and comprehensive standards that will be consistently enforced. It is also critical that Uefa provides specific details of the processes it plans to adopt in reviewing all games under its jurisdiction."

Before today's decision, Arsenal had submitted a 19-page response to Uefa's charges, arguing that having also studied the video evidence, they felt that there was some element of contact from Boruc. They believed the footage Uefa sent them showed this and, therefore, the governing body's analysis was flawed.

Moreover, Arsenal contended it was impossible for Uefa or anybody to read any intention to deceive into Eduardo's tumble. They pointed out that he did not appeal for a foul and stressed Eduardo's blemish-free disciplinary record and the fact that, following his horrific leg break at Birmingham City in February 2008, he is generally mindful of the need to pull out of potential collisions.

Arsenal must decide whether to appeal within the next three days. The player himself is currently on international duty with Croatia.